This project has several related aspects concerned with developing the use of Body Surface Potential Maps in clinical diagnosis. 1. Correlation of BSPM with cardiac physiology and pathology in pediatric clinical studies, particulary of patients undergoing catheterization. As part of this research, a data base of normals as well as abnormals will be collected. As much as possible, non-ECG diagnostic data will be utilized. Correlation of BSPM with conventional ECG and VCG will also be examined. 2. Improvement in data manipulation and display, seeking simple methodology for generating and storing maps that will permit rapid retrieval and ability to view maps, be they stationary or animated. Pattern recognition techniques will be explored, including use of grey-level display, pseudo-color, and three-dimensional schemes. Display of integrated values such as ventricular gradient. 3. Normalization of maps to eliminate the effect of body shape and surface inhomogeneity. 4. Improvement in the technology for applying the large number of electrodes (180) will be sought in the form of a "vest" such that procedure will be rapid and require neither skin or electrode preparation. The use of active dry electrodes facilitates this design.